Method of making laminated cores



METHOD OF. MAKING LAMINATED CORES Filed Aug. 8, 1967 FIGZ F163 3,497,949 METHOD OF MAKING LAMINATED CORES John Salt, Shenstone, Lichfield, England, assignor to Joseph Lucas (Industries) Limited, Birmingham, England, a British company Filed Aug. 8, 1967, Ser. No. 659,171 Claims priority, application Great Britain, Aug. 8, 1966, 35,374/ 66 Int. Cl. H01f 3/ 04 U.S. Cl. 29-609 3 Claims ABSTRACT OF THE DISCLOSURE A method of manufacturing laminated cores comprising, stacking a plurality of generally rectangular laminae to form a pile, and subjecting said pile, along at least part of its length, to an operation whereby some or all of the laminae are deformed to produce a pile which will fit into a cylinder of smaller diameter than that into which the original pile will fit.

This invention relates to a method of manufacturing laminated cores particularly but not exclusively intended for use in ignition coils.

A method according to the invention comprises, stacking a plurality of generally rectangular laminae to form a pile, and subjecting said pile, along at least part of its length to an operation whereby some or all of the laminae are deformed to produce a pile which Will fit into a cylinder of smaller diameter than that into which the original pile will fit.

The invention further resides in a core formed as specified in the preceding paragraph.

One example of the invention is illustrated in the accompanying drawings wherein:

FIGURE 1 is a side elevational view of a core manufactured in accordance with the invention and intended for use in an ignition coil, and

FIGURES 2 and 3 are sectional views on the lines 22 and 3-3 respectively in 'FIGURE 1.

Referring to the drawings, the core 11 is manufactured from a plurality of laminae 12. The individual rectangular laminae are stacked to form a pile of rectangular crosssection (FIGURE 3). The pile of laminae is then stamped in a coining press to shape at least part of the pile to a circular cross-section (FIGURE 2). The pile is then bound with adhesive strip to hold the laminae together. The deformation of the pile enables a former of smaller diameter to be used than is at present used with known "United States Patent "ice cores, and the smaller former serves in turn to allow a reduction in the amount of Wire in the coil windings.

Preferably, one end of the core is left undeformed as shown so that it can be engaged in a complementarily shaped bore in a known form of base member for an ignition coil.

It will be appreciated that cores having cross-sectional shapes other than circular could be produced by this method, provided that the finished pile will fit into a cylinder of smaller diameter than that into which the original pile will fit.

In a modification the pile of laminae is spot welded to secure the laminae together in the pile prior to the stamping operation.

Having thus described my invention what I claim as new and desire to secure by Letters Patent is:

1. A method of manufacturing laminated cores comprising, stacking a plurality of elongated, generally rectangular laminae to form a pile in which the laminae are parallel, and deforming the pile along part of its length so that the deformed parts of the laminae on both sides of a median plane of the pile parallel with the laminae, are generally concave with respect to the median plane, so that the deformed portion of the pile is of generally circular cross section and will fit into'a cylinder of smaller diameter than that into which the original pile will fit, the undeformed portion of the pile being at one end of the pile.

2. A method as claimed in claim 1 including the subsequent step of binding the pile to hold the laminations together.

3. A method as claimed in claim 1 including the step of spot welding the pile of laminae to secure the laminae together in the pile prior to the deforming operation.

References Cited UNITED STATES PATENTS 1,857,215 5/1932 Ruder 29-609 X 2,280,981 4/1942 Schuh 336-234 X 2,523,071 9/1950 Somerville 29-609 X 2,671,951 3/1954 Sliwiak 336234 X 3,303,449 2/1967 Stimler 336234 X 3,307,132 2/1967 Ellis 29-609 X 3,408,734 11/1968 Leahy et a1. 29-609 X JOHN F. CAMPBELL, Primary Examiner C. E. HALL, Assistant Examiner U.S. Cl. X.R. 

